Mode profile of (a) the TM-like (electric field: E‖z) and (b) TE-like (electric field: E‖x) fundamental mode of the pump and signal waves in the GaP rib waveguide. The wavelength of the pump and signal sources are 1.55 and 1.559 μm, respectively.

(a) Calculated THz output power PTHz for the GaP-based hybrid waveguide structure. The waveguide length and incident power were L=10, 20, and 40 mm and Pp=Ps=1W, respectively. (b) Power conversion efficiency for 5.93 THz generation and bandwidth as a function of the waveguide length.